Golf ball with improved flight performance

ABSTRACT

A golf ball with aerodynamic coefficient magnitude and aerodynamic force angle, resulting in improved flight performance, such as increased carry and flight consistency regardless of ball orientation. In particular, the present invention is directed to a golf ball having increased flight distance as defined by a set of aerodynamic requirements at certain spin ratios and Reynolds Numbers, and more particularly the golf ball has a low lift coefficient at a high Reynolds Number.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/108,812, filed Apr. 19, 2005, which is a continuation of U.S. patentapplication Ser. No. 10/784,744, filed Feb. 24, 2004, now U.S. Pat. No.6,913,550, which is a continuation of U.S. patent application Ser. No.10/096,852, filed Mar. 14, 2002, now U.S. Pat. No. 6,729,976, which is acontinuation-in-part of U.S. patent application Ser. No. 09/989,191,filed Nov. 21, 2001, now U.S. Pat. No. 6,796,912, and also acontinuation-in-part of U.S. patent application Ser. No. 09/404,164,filed Sep. 27, 1999, now U.S. Pat. No. 6,358,161, which is a divisionalof U.S. patent application Ser. No. 08/922,633, filed Sep. 3, 1997, nowU.S. Pat. No. 5,957,786. The entire disclosures of the relatedapplications are incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to golf balls having improved aerodynamiccharacteristics that yield improved flight performance and longer ballflight. The improved aerodynamic characteristics are obtained throughthe use of specific dimple arrangements and dimple profiles. Theaerodynamic improvements are applicable to golf balls of any size andweight. The invention further relates to golf balls with symmetricflight characteristics.

BACKGROUND OF THE INVENTION

The flight of a golf ball is determined by many factors, however, themajority of the properties that determine flight are outside of thecontrol of a golfer. While a golfer can control the speed, the launchangle, and the spin rate of a golf ball by hitting the ball with aparticular club, the final resting point of the ball depends upon golfball construction and materials, as well as environmental conditions,e.g., terrain and weather. Since flight distance and consistency arecritical factor in reducing golf scores, manufacturers continuallystrive to make even the slightest incremental improvements in golf ballflight consistency and flight distance, e.g., one or more yards, throughvarious aerodynamic properties and golf ball constructions. Flightconsistency is a significant problem for manufacturers because the manyof golf ball dimple patterns and/or dimple shapes that yield increasedflight distance also result in asymmetric flight performance. Asymmetricflight performance prescribes that the overall flight distance is afunction of ball orientation when struck with a club.

Historically, manufacturers improved flight performance via iterativetesting, where golf balls with numerous dimple patterns and dimpleprofiles are produced and tested using mechanical golfers. Flightperformance is characterized in these tests by measuring the landingposition of the various ball designs. To determine if a particular balldesign has desirable flight characteristics for a broad range ofplayers, i.e., high and low swing speed players, manufacturers performthe mechanical golfer test with different ball launch conditions, whichinvolves immense time and financial commitments. Furthermore, it isdifficult to identify incremental performance improvements using thesemethods due to the statistical noise generated by environmentalconditions, which necessitates large sample sizes for sufficientconfidence intervals.

Another more precise method of determining specific dimple arrangementsand dimple shapes that results in an aerodynamic advantage involves thedirect measurement of aerodynamic characteristics as opposed to balllanding positions. These aerodynamic characteristics define the forcesacting upon the golf ball throughout flight.

Aerodynamic forces acting on a golf ball are typically resolved intoorthogonal components of lift and drag. Lift is defined as theaerodynamic force component acting perpendicular to the flight path. Itresults from a difference in pressure that is created by a distortion inthe air flow that results from the back spin of the ball. A boundarylayer forms at the stagnation point of the ball, B, then grows andseparates at points S1 and S2, as shown in FIG. 1. Due to the ballbackspin, the top of the ball moves in the direction of the airflow,which retards the separation of the boundary layer. In contrast, thebottom of the ball moves against the direction of airflow, thusadvancing the separation of the boundary layer at the bottom of theball. Therefore, the position of separation of the boundary layer at thetop of the ball, S1, is further back than the position of separation ofthe boundary layer at the bottom of the ball, S2. This asymmetricalseparation creates an arch in the flow pattern, requiring the air overthe top of the ball to move faster and, thus, have lower pressure thanthe air underneath the ball.

Drag is defined as the aerodynamic force component acting parallel tothe ball flight direction. As the ball travels through the air, the airsurrounding the ball has different velocities and, accordingly,different pressures. The air exerts maximum pressure at the stagnationpoint, B, on the front of the ball, as shown in FIG. 1. The air thenflows over the sides of the ball and has increased velocity and reducedpressure. The air separates from the surface of the ball at points S1and S2, leaving a large turbulent flow area with low pressure, i.e., thewake. The difference between the high pressure in front of the ball andthe low pressure behind the ball reduces the ball speed and acts as theprimary source of drag for a golf ball.

The dimples on a golf ball are used to adjust drag and lift propertiesof a golf ball and, therefore, the majority of golf ball manufacturersresearch dimple patterns, shape, volume, and cross-section in order toimprove overall flight distance of a golf ball. The dimples create athin turbulent boundary layer around the ball. The turbulence energizesthe boundary layer and aids in maintaining attachment to and around theball to reduce the area of the wake. The pressure behind the ball isincreased and the drag is substantially reduced.

There is minimal prior art disclosing preferred aerodynamiccharacteristics for golf balls. U.S. Pat. No. 5,935,023 disclosespreferred lift and drag coefficients for a single speed with afunctional dependence on spin ratio. U.S. Pat. Nos. 6,213,898 and6,290,615 disclose golf ball dimple patterns that reduce high-speed dragand increase low speed lift. It has now been discovered, contrary to thedisclosures of these patents, that reduced high-speed drag and increasedlow speed lift does not necessarily result in improved flightperformance. For example, excessive high-speed lift or excessivelow-speed drag may result in undesirable flight performancecharacteristics. The prior art is silent, however, as to aerodynamicfeatures that influence other portions of golf ball flight, such asflight consistency, as well as enhanced aerodynamic coefficients forballs of varying size and weight.

Thus, there is a need to optimize the aerodynamics of a golf ball toimprove flight distance and consistency. There is also a need to developdimple arrangements and profiles that result in longer distance and moreconsistent flights regardless of the swing-speed of a player, theorientation of the ball when impacted, or the physical properties of theball being played.

SUMMARY OF THE INVENTION

The present invention is directed to a golf ball with improvedaerodynamic performance. In one embodiment, a golf ball with a pluralityof dimples has an aerodynamic coefficient magnitude defined byC_(mag)=√C_(L) ²+C_(D) ²) and an aerodynamic force angle defined byAngle=tan⁻¹(C_(L)/C_(D)), wherein C_(L) is a lift coefficient and C_(D)is a drag coefficient, wherein the golf ball has a first aerodynamiccoefficient magnitude from about 0.24 to about 0.27 and a firstaerodynamic force angle of about 31 degrees to about 35 degrees at aReynolds Number of about 230000 and a spin ratio of about 0.085 and asecond aerodynamic coefficient magnitude from about 0.25 to about 0.28and a second aerodynamic force angle of about 34 degrees to about 38degrees at a Reynolds Number of about 207000 and a spin ratio of about0.095.

In another embodiment, the golf ball has a third aerodynamic coefficientmagnitude from about 0.26 to about 0.29 and a third aerodynamic forceangle from about 35 degrees to about 39 degrees at a Reynolds Number ofabout 184000 and a spin ratio of about 0.106 and a fourth aerodynamiccoefficient magnitude from about 0.27 to about 0.30 and a fourthaerodynamic force angle of about 37 degrees to about 42 degrees at aReynolds Number of about 161000 and a spin ratio of about 0.122. In yetanother embodiment, a fifth aerodynamic coefficient magnitude is fromabout 0.29 to about 0.32 and a fifth aerodynamic force angle is fromabout 39 degrees to about 43 degrees at a Reynolds Number of about138000 and a spin ratio of about 0.142 and a sixth aerodynamiccoefficient magnitude is from about 0.32 to about 0.35 and a sixthaerodynamic force angle is from about 40 degrees to about 44 degrees ata Reynolds Number of about 115000 and a spin ratio of about 0.170. In afurther embodiment, the golf ball has a seventh aerodynamic coefficientmagnitude from about 0.36 to about 0.40 and a seventh aerodynamic forceangle of about 41 degrees to about 45 degrees at a Reynolds Number ofabout 92000 and a spin ratio of about 0.213 and an eighth aerodynamiccoefficient magnitude from about 0.40 to about 0.45 and an eighthaerodynamic force angle of about 40 degrees to about 44 degrees at aReynolds Number of about 69000 and a spin ratio of about 0.284.

The aerodynamic coefficient magnitudes may vary from each other by about6 percent or less, and more preferably, about 3 percent or less, at anytwo axes of ball rotation. In another embodiment, the plurality ofdimples cover about 80 percent or greater of the ball surface. In yetanother embodiment, at least 80 percent of the dimples have a diametergreater than about 6.5 percent of the ball diameter. The dimples arepreferably arranged in an icosahedron or an octahedron pattern. In oneembodiment, the dimples have at least three different dimple diameters.In another embodiment, at least 10 percent of the plurality of dimpleshave a shape defined by catenary curve. In yet another embodiment, atleast a first portion of the dimples have a shape factor of less than 60and a second portion of the dimples have a shape factor of greater than60. The golf ball may have at least one core and at least one coverlayer, wherein at least one of the layers comprises urethane, ionomer,balata, polyurethane, and mixtures thereof.

The present invention is also directed to a golf ball with a pluralityof dimples having an aerodynamic coefficient magnitude defined byC_(mag)=√(C_(L) ²+C_(D) ²) and an aerodynamic force angle defined byAngle=tan⁻¹ (C_(L)/C_(D)), wherein C_(L) is a lift coefficient and C_(D)is a drag coefficient, wherein the golf ball comprises a firstaerodynamic coefficient magnitude from about 0.40 to about 0.45 and afirst aerodynamic force angle of about 40 degrees to about 44 degrees ata Reynolds Number of about 69000 and a spin ratio of about 0.284 and asecond aerodynamic coefficient magnitude from about 0.36 to about 0.40and a second aerodynamic force angle of about 41 degrees to about 45degrees at a Reynolds Number of about 92000 and a spin ratio of about0.213.

The golf ball may also have a third aerodynamic coefficient magnitudefrom about 0.32 to about 0.35 and a third aerodynamic force angle ofabout 40 degrees to about 44 degrees at a Reynolds Number of about115000 and a spin ratio of about 0.170 and a fourth aerodynamiccoefficient magnitude from about 0.29 to about 0.32 and a fourthaerodynamic force angle of about 39 degrees to about 43 degrees at aReynolds Number of about 138000 and a spin ratio of about 0.142. Inanother embodiment, the golf ball has a fifth aerodynamic coefficientmagnitude from about 0.27 to about 0.30 and a fifth aerodynamic forceangle of about 37 degrees to about 42 degrees at a Reynolds Number ofabout 161000 and a spin ratio of about 0.122 and a sixth aerodynamiccoefficient magnitude from about 0.26 to about 0.29 and a sixthaerodynamic force angle of about 35 degrees to about 39 degrees at aReynolds Number of about 184000 and a spin ratio of about 0.106.

In one embodiment, the aerodynamic coefficient magnitudes vary from eachother by about 6 percent, and more preferably, about 3 percent, or lessat any two axes of ball rotation. In another embodiment, the pluralityof dimples cover about 80 percent or greater of the ball surface. In yetanother embodiment, at least 80 percent of the dimples have a diametergreater than about 6.5 percent of the ball diameter and the dimples arepreferably arranged in an icosahedron or an octahedron pattern. In oneembodiment, the dimples have at least three different dimple diameters.In another embodiment, at least 10 percent of the plurality of dimpleshave a shape defined by catenary curve. In yet another embodiment, atleast a first portion of the dimples have a shape factor of less than 60and a second portion of the dimples have a shape factor of greater than60. The golf ball may have at least one core and at least one coverlayer, wherein at least one of the layers comprises urethane, ionomer,balata, polyurethane, and mixtures thereof.

The present invention is also related to a golf ball with a plurality ofdimples having an aerodynamic coefficient magnitude defined byC_(mag)=√(C_(L) ²+C_(D) ²) and an aerodynamic force angle defined byAngle=tan⁻¹ (C_(L)/C_(D)), wherein C_(L) is a lift coefficient and C_(D)is a drag coefficient, wherein the golf ball has a first aerodynamiccoefficient magnitude from about 0.40 to about 0.45 and a firstaerodynamic force angle of about 40 degrees to about 44 degrees at aReynolds Number of about 69000 and a spin ratio of about 0.284 for aball weight W of 1.62 ounces and a diameter D of 1.68 inches and asecond aerodynamic coefficient magnitude from about 0.36 to about 0.40and a second aerodynamic force angle of about 41 degrees to about 45degrees at a Reynolds Number of about 92000 and a spin ratio of about0.213 for a ball weight of 1.62 ounces and a diameter of 1.68 inches,wherein the aerodynamic coefficient magnitudes and force angles areadjusted for ball weight and diameter in the following manner:Adjusted C _(mag) =C_(mag)√(sin(Angle)*(W/1.62)*(1.68/D)²)²+(cos(Angle))²)Adjusted Angle=tan⁻¹(tan(Angle)*(W/1.62)*(1.68/D)²).

The golf ball may also have a third aerodynamic coefficient magnitudefrom about 0.32 to about 0.35 and a third aerodynamic force angle ofabout 40 degrees to about 44 degrees at a Reynolds Number of about115000 and a spin ratio of about 0.170 and a fourth aerodynamiccoefficient magnitude from about 0.29 to about 0.32 and a fourthaerodynamic force angle of about 39 degrees to about 43 degrees at aReynolds Number of about 138000 and a spin ratio of about 0.142. Inanother embodiment, the golf ball has a fifth aerodynamic coefficientmagnitude from about 0.27 to about 0.30 and a fifth aerodynamic forceangle of about 37 degrees to about 42 degrees at a Reynolds Number ofabout 161000 and a spin ratio of about 0.122 and a sixth aerodynamiccoefficient magnitude from about 0.26 to about 0.29 and a sixthaerodynamic force angle of about 35 degrees to about 39 degrees at aReynolds Number of about 184000 and a spin ratio of about 0.106. In yetanother embodiment, a seventh aerodynamic coefficient magnitude is fromabout 0.25 to about 0.28 and a seventh aerodynamic force angle is fromabout 34 degrees to about 38 degrees at a Reynolds Number of about207000 and a spin ratio of about 0.095 and an eighth aerodynamiccoefficient magnitude is from about 0.24 to about 0.27 and an eighthaerodynamic force angle is from about 31 degrees to about 35 degrees ata Reynolds Number of about 230000 and a spin ratio of about 0.085.

In one embodiment, the aerodynamic coefficient magnitudes vary from eachother by about 6 percent, and more preferably, about 3 percent, or lessat any two axes of ball rotation. In another embodiment, the pluralityof dimples cover about 80 percent or greater of the ball surface. In yetanother embodiment, at least 80 percent of the dimples have a diametergreater than about 6.5 percent of the ball diameter and the dimples arepreferably arranged in an icosahedron or an octahedron pattern. In oneembodiment, the dimples have at least three different dimple diameters.In another embodiment, at least 10 percent of the plurality of dimpleshave a shape defined by catenary curve. In yet another embodiment, atleast a first portion of the dimples have a shape factor of less than 60and a second portion of the dimples have a shape factor of greater than60. The golf ball may have at least one core and at least one coverlayer, wherein at least one of the layers comprises urethane, ionomer,balata, polyurethane, and mixtures thereof.

The present invention is further directed to a golf ball with aplurality of dimples having an aerodynamic coefficient magnitude definedby C_(mag)=√C_(L) ^(2+C) _(D) ²) and an aerodynamic force angle definedby Angle=tan⁻¹ (C_(L)/C_(D)), wherein C_(L) is a lift coefficient andC_(D) is a drag coefficient, wherein the golf ball has a firstaerodynamic coefficient magnitude from about 0.40 to about 0.44 and afirst aerodynamic force angle of about 40 degrees to about 42 degrees ata Reynolds Number of about 69000 and a spin ratio of about 0.284 and asecond aerodynamic coefficient magnitude from about 0.36 to about 0.39and a second aerodynamic force angle of about 41 degrees to about 43degrees at a Reynolds Number of about 92000 and a spin ratio of about0.213.

In one embodiment, the golf ball further includes a third aerodynamiccoefficient magnitude from about 0.32 to about 0.344 and a thirdaerodynamic force angle of about 40 degrees to about 42 degrees at aReynolds Number of about 115000 and a spin ratio of about 0.170 and afourth aerodynamic coefficient magnitude from about 0.29 to about 0.311and a fourth aerodynamic force angle of about 39 degrees to about 41degrees at a Reynolds Number of about 138000 and a spin ratio of about0.142. The golf ball may also include a fifth aerodynamic coefficientmagnitude from about 0.27 to about 0.291 and a fifth aerodynamic forceangle of about 37 degrees to about 40 degrees at a Reynolds Number ofabout 161000 and a spin ratio of about 0.122 and a sixth aerodynamiccoefficient magnitude from about 0.26 to about 0.28 and a sixthaerodynamic force angle of about 35 degrees to about 38 degrees at aReynolds Number of about 184000 and a spin ratio of about 0.106. Inanother embodiment, a seventh aerodynamic coefficient magnitude fromabout 0.25 to about 0.271 and a seventh aerodynamic force angle of about34 degrees to about 36 degrees at a Reynolds Number of about 207000 anda spin ratio of about 0.095 and an eighth aerodynamic coefficientmagnitude from about 0.24 to about 0.265 and an eighth aerodynamic forceangle of about 31 degrees to about 33 degrees at a Reynolds Number ofabout 230000 and a spin ratio of about 0.085 may further define the golfball.

In one embodiment, the aerodynamic coefficient magnitudes vary from eachother by about 6 percent, and more preferably, about 3 percent, or lessat any two axes of ball rotation. In another embodiment, the pluralityof dimples cover about 80 percent or greater of the ball surface. In yetanother embodiment, at least 80 percent of the dimples have a diametergreater than about 6.5 percent of the ball diameter and the dimples arepreferably arranged in an icosahedron or an octahedron pattern. In oneembodiment, the dimples have at least three different dimple diameters.In another embodiment, at least 10 percent of the plurality of dimpleshave a shape defined by catenary curve. In yet another embodiment, atleast a first portion of the dimples have a shape factor of less than 60and a second portion of the dimples have a shape factor of greater than60. The golf ball may have at least one core and at least one coverlayer, wherein at least one of the layers comprises urethane, ionomer,balata, polyurethane, and mixtures thereof.

The present invention is also directed to a golf ball dimple patternthat provides a surprisingly better dimple packing than any previouspattern so that a greater percentage of the surface of the golf ball iscovered by dimples. The prior art golf balls have dimple patterns thatleave many large spaces between adjacent dimples and/or use smalldimples to fill in the spaces. The golf balls according to the presentinvention have triangular regions with a plurality of dimple sizesarranged to provide a remarkably high percentage of dimple coveragewhile avoiding groupings of relatively large dimples.

The triangular regions have a first set of dimples formed in a largetriangle and a second set of dimples formed in a small triangle insideof and adjacent to the large triangle. The first set of dimples formingthe large triangle comprises dimples that increase in size from thedimples on the points of the triangle toward the midpoint of thetriangle side. Thus, the dimples close to or on the midpoint of thesides of the triangle are the largest dimples on the large triangle.Each dimple diameter along the triangle side is equal to or greater thanthe adjacent dimple toward the vertex or triangle point. Through thislayout and with proper sizing, as set forth below, the dimple coverageis greater than 80 percent of the surface of the golf ball.

Further, the dimples are arranged so that there are three or less greatcircle paths that do not intersect any dimples to minimize undimpledsurface area. Great circles take up a significant amount of the surfacearea and an intersection of more than two great circles creates verysmall angles that have to be filled with very small dimples or largegaps are created.

Still further, the dimples are arranged such that there are no more thantwo adjacent dimples of the largest diameter. Thus, the largest dimplesare more evenly spaced over the ball and are not clumped together.

In one embodiment of the present invention, dimples cover more than 80percent of the outer surface. More importantly, the dimple coverage isnot accomplished by the mere addition of very small dimples that do noteffectively contribute to the creation of turbulence. In a preferredembodiment, the total number of dimples is about 300 to about 500 and atleast about 80 percent of the dimples have a diameter of about 0.11inches or greater, and, more preferably, at least about 90 percent ofthe dimples have a diameter of about 0.11 inches or greater. Morepreferably, at least about 95 percent of the dimples have a diameter ofabout 0.11 inches or greater.

In another embodiment of the present invention, the golf ball has anicosahedron dimple pattern. The pattern includes 20 triangles made fromabout 362 dimples and does not have a great circle that does notintersect any dimples. Each of the large triangles, preferably, has anodd number of dimples (7) along each side and the small triangles havean even number of dimples (4) along each side. To properly pack thedimples, the large triangle has nine more dimples than the smalltriangle. In another embodiment, the ball has five different sizes ofdimples in total. The sides of the large triangle have four differentsizes of dimples and the small triangles have two different sizes ofdimples.

In yet another embodiment of the present invention, the golf ball has anicosahedron dimple pattern with a large triangle including threedifferent dimples and the small triangles having only one diameter ofdimple. In a preferred embodiment, there are 392 dimples and one greatcircle that does not intersect any dimples. In another embodiment, morethan five alternative dimple diameters are used.

In one embodiment of the present invention, the golf ball has anoctahedron dimple pattern. The pattern includes eight triangles madefrom about 440 dimples and has three great circles that do not intersectany dimples. In the octahedron pattern, the pattern includes a third setof dimples formed in a smallest triangle inside of and adjacent to thesmall triangle. To properly pack the dimples, the large triangle hasnine more dimples than the small triangle and the small triangle hasnine more dimples than the smallest triangle. In this embodiment, theball has six different dimple diameters distributed over the surface ofthe ball. The large triangle has five different dimple diameters, thesmall triangle has three different dimple diameters and the smallesttriangle has two different dimple diameters.

The present invention is also directed to defining the dimple profile ona golf ball by revolving a catenary curve about its symmetrical axis. Inone embodiment, the catenary curve used to define a golf ball dimple isa hyperbolic cosine function in the form of:Y=(d(cos h(ax)−1))/(cos h(ar)−1)where:

Y is the vertical distance from the dimple apex,

x is the radial distance from the dimple apex,

a is the shape constant;

d is the depth of the dimple, and

r is the radius of the dimple (r=D/2)

D is the dimple diameter.

In one embodiment, at least 10 percent of the dimples have a shapedefined by the revolution of a catenary curve. In another embodiment, atleast 10 percent of the dimples have a shape factor, a, of greater than60. In yet another embodiment, at least two different catenary shapefactors are used to define dimple profiles on the golf ball. In oneembodiment, at least 20 percent of the dimples have a catenary shapefactor of less than 60 and at least 20 percent of the dimples have ashape factor of greater than 70. In another embodiment, at least threedimple profiles on the golf ball are defined by at least three differentcatenary shape factors.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention may be more fullyunderstood with reference to, but not limited by, the followingdrawings.

FIG. 1 is an illustration of the air flow on a golf ball in flight;

FIG. 2 is an illustration of the forces acting on a golf ball in flight;

FIG. 3 is a graph of the magnitude of aerodynamic coefficients versusReynolds Number for a golf ball made according to the present inventionand a prior art golf ball;

FIG. 4 is a graph of the angle of aerodynamic force versus ReynoldsNumber for a golf ball made according to the present invention and aprior art golf ball;

FIG. 5 is an isometric view of the icosahedron pattern used on the priorart TITLEIST PROFESSIONAL ball showing dimple sizes;

FIG. 6 is an isometric view of the icosahedron pattern used on the priorart TITLEIST PROFESSIONAL ball showing the triangular regions formed bythe icosahedron pattern;

FIG. 7 is an isometric view of a first embodiment of a golf ballaccording to the present invention having an icosahedron pattern,showing dimple sizes;

FIG. 8 is a top view of the golf ball in FIG. 7, showing dimple sizesand arrangement;

FIG. 9 is an isometric view of a second embodiment of a golf ballaccording to the present invention having an icosahedron pattern,showing dimple sizes and the triangular regions formed from theicosahedron pattern;

FIG. 10 is a top view of the golf ball in FIG. 9, showing dimple sizesand arrangement;

FIG. 11 is a top view of the golf ball in FIG. 9, showing dimplearrangement;

FIG. 12 is a side view of the golf ball in FIG. 9, showing the dimplearrangement at the equator;

FIG. 13 is a spherical-triangular region of a golf ball according to thepresent invention having an octahedral dimple pattern, showing dimplesizes;

FIG. 14 is the spherical triangular region of FIG. 13, showing thetriangular dimple arrangement;

FIG. 15 shows a method for measuring the depth and radius of a dimple;

FIG. 16 is a dimple cross-sectional profile defined by a hyperboliccosine function, cosh, with a shape constant of 20, a dimple depth of0.025 inches, a dimple radius of 0.05 inches, and a volume ratio of0.51;

FIG. 17 is a dimple cross-sectional profile defined by a hyperboliccosine function, cosh, with a shape constant of 40, a dimple depth of0.025 inches, a dimple radius of 0.05 inches, and a volume ratio of0.55;

FIG. 18 is a dimple cross-sectional profile defined by a hyperboliccosine function, cosh, with a shape constant of 60, a dimple depth of0.025 inches, a dimple radius of 0.05 inches, and a volume ratio of0.60;

FIG. 19 is a dimple cross-sectional profile defined by a hyperboliccosine function, cosh, with a shape constant of 80, a dimple depth of0.025 inches, a dimple radius of 0.05 inches, and a volume ratio of0.64;

FIG. 20 is a dimple cross-sectional profile defined by a hyperboliccosine function, cosh, with a shape constant of 100, a dimple depth of0.025 inches, a dimple radius of 0.05 inches, and a volume ratio of0.69; and

FIG. 21 is a graph illustrating the coordinate system in a dimplepattern according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to golf balls having improvedaerodynamic efficiency, resulting in uniformly increased flight distancefor golfers of all swing speeds. In particular, the present invention isdirected to the selection of dimple arrangements and dimple profiles toobtain a unique set of aerodynamic criteria, which results inconsistently improved aerodynamic efficiency. The desired aerodynamiccriteria are defined by the magnitude and direction of the aerodynamicforce, for the range of Spin Ratios and Reynolds Numbers that encompassthe flight regime for typical golf ball trajectories.

Aerodynamic Force

The forces acting on a golf ball in flight are enumerated in Equation 1and illustrated in FIG. 2:F=F _(L) +F _(D) +F _(G)  (Eq. 1)Where

F=total force acting on the ball

F_(L)=lift force

F_(D)=drag force

F_(G)=gravity force

The lift force (F_(L)) acts in a direction dictated by the cross productof the spin vector and the velocity vector. The drag force (F_(D)) actsin a direction that is directly opposite the velocity vector. The liftand drag forces of Equation 1 are calculated in Equations 2 and 3,respectively:F _(L)=0.5C _(L) ρAV ²  (Eq. 2)F _(D)=0.5C _(D) ρAV ²  (Eq. 3)where

ρ=density of air (slugs/ft³)

A=projected area of the ball (ft²) ((π/4)D²)

D=ball diameter (ft)

V=ball velocity (ft/s)

C_(L)=dimensionless lift coefficient

C_(D)=dimensionless drag coefficient

Lift and drag coefficients are used to quantify the force imparted to aball in flight and are dependent on air density, air viscosity, ballspeed, and spin rate; the influence of all these parameters may becaptured by two dimensionless parameters Spin Ratio (SR) and ReynoldsNumber (N_(Re)). Spin Ratio is the rotational surface speed of the balldivided by ball velocity. Reynolds Number quantifies the ratio ofinertial to viscous forces acting on the golf ball moving through air.SR and N_(Re) are calculated in Equations 4 and 5 below:SR=ω(D/2)/V  (Eq. 4)N _(Re) =DVρ/μ  (Eq. 5)where

ω=ball rotation rate (radians/s) (2π(RPS))

RPS=ball rotation rate (revolution/s)

V=ball velocity (ft/s)

D=ball diameter (ft)

ρ=air density (slugs/ft³)

μ=absolute viscosity of air (lb/ft-s)

There are a number of suitable methods for determining the lift and dragcoefficients for a given range of SR and N_(Re), which include the useof indoor test ranges with ballistic screen technology. U.S. Pat. No.5,682,230, the entire disclosure of which is incorporated by referenceherein, teach the use of a series of ballistic screens to acquire liftand drag coefficients. U.S. Pat. Nos. 6,186,002 and 6,285,445, alsoincorporated in their entirety by reference herein, disclose methods fordetermining lift and drag coefficients for a given range of velocitiesand spin rates using an indoor test range, wherein the values for C_(L)and C_(D) are related to SR and N_(Re) for each shot. One skilled in theart of golf ball aerodynamics testing could readily determine the liftand drag coefficients through the use of an indoor test range.

The present invention is directed to a golf ball having improved flightdistance as defined by two novel parameters that account for both liftand drag simultaneously: 1) the magnitude of aerodynamic force(C_(mag)); and 2) the direction of the aerodynamic force (Angle). It hasnow been discovered that flight performance improvements are attainedwhen the dimple pattern and dimple profiles are selected to satisfyspecific magnitude and direction criteria. The magnitude and angle ofthe aerodynamic force are linearly related to the lift and dragcoefficients and, therefore, the magnitude and angle of the aerodynamiccoefficients are used to establish the preferred criteria. The magnitudeand the angle of the aerodynamic coefficients are defined in Equations 6and 7 below:C _(mag)=√(C _(L) ² +C _(D) ²)  (Eq. 6)Angle=tan⁻¹(C _(L) /C _(D))  (Eq. 7)

Table 1 illustrates the aerodynamic criteria for a golf ball of thepresent invention that results in increased flight distances. Thecriteria are specified as low, median, and high C_(mag) and Angle foreight specific combinations of SR and N_(Re). Golf balls with C_(mag)and Angle values between the low and the high number are preferred. Morepreferably, the golf balls of the invention have C_(mag) and Anglevalues between the low and the median numbers delineated in Table 1. TheC_(mag) values delineated in Table 1 are intended for golf balls thatconform to USGA size and weight regulations. The size and weight of thegolf balls used with the aerodynamic criteria of Table 1 are 1.68 inchesand 1.62 ounces, respectively. TABLE 1 AERODYNAMIC CHARACTRISTICS BALLDIAMETER = 1.68 INCHES, BALL WEIGHT = 1.62 OUNCES Magnitude¹ Angle² (0)N_(Re) SR Low Median High Low Median High 230000 0.085 0.24 0.265 0.2731 33 35 207000 0.095 0.25 0.271 0.28 34 36 38 184000 0.106 0.26 0.2800.29 35 38 39 161000 0.122 0.27 0.291 0.30 37 40 42 138000 0.142 0.290.311 0.32 38 41 43 115000 0.170 0.32 0.344 0.35 40 42 44  92000 0.2130.36 0.390 0.40 41 43 45  69000 0.284 0.40 0.440 0.45 40 42 44¹As defined by Eq. 6²As defined by Eq. 7

To ensure consistent flight performance regardless of ball orientation,the percent deviation of C_(mag) for each of the SR and N_(Re)combinations listed in Table 1 plays an important role. The percentdeviation of C_(mag) may be calculated in accordance with Equation 8,wherein the ratio of the absolute value of the difference between theC_(mag) for two orientations to the average of the C_(mag) for the twoorientations is multiplied by 100.Percent deviation C _(mag)=|(C _(mag1) −C _(mag2))|/((C _(mag1) +C_(mag2))/2)*100  (Eq. 8)where

C_(mag1)=C_(mag) for orientation 1

C_(mag2)=C_(mag) for orientation 2

In one embodiment, the percent deviation is about 6 percent or less. Inanother embodiment, the deviation of C_(mag) is about 3 percent or less.To achieve the consistent flight performance, the percent deviationcriteria of Equation 8 is preferably satisfied for each of the eightC_(mag) values associated with the eight SR and N_(Re) values containedin Table 1.

Aerodynamic asymmetry typically arises from parting lines inherent inthe dimple arrangement or from parting lines associated with themanufacturing process. The percent C_(mag) deviation should be obtainedusing C_(mag) values measured with the axis of rotation normal to theparting line, commonly referred to as a poles horizontal, PH,orientation and C_(mag) values measured in an orientation orthogonal toPH, commonly referred to as a pole over pole, PP orientation. Themaximum aerodynamic asymmetry is generally measured between the PP andPH orientation.

One of ordinary skill in the art would be aware, however, that thepercent deviation of C_(mag) as outlined above applies to PH and PP, aswell as any other two orientations. For example, if a particular dimplepattern is used having a great circle of shallow dimples, which will bedescribed in greater detail below, different orientations should bemeasured. The axis of rotation to be used for measurement of symmetry inthe above example scenario would be normal to the plane described by thegreat circle and coincident to the plane of the great circle.

It has also been discovered that the C_(mag) and Angle criteriadelineated in Table 1 for golf balls with a nominal diameter of 1.68 anda nominal weight of 1.62 ounces may be advantageously scaled to obtainthe similar optimized criteria for golf balls of any size and weight.The aerodynamic criteria of Table 1 may be adjusted to obtain theC_(mag) and angle for golf balls of any size and weight in accordancewith Equations 9 and 10.C _(mag(ball)) =C _(mag(Table 1))√(sin(Angle_((Table1)))*(W_(ba11)/1.62)*(1.68/D _(ball)))²+(cos(Angle_((Table1)))²)  (Eq. 9)Angle_((ball))=tan⁻¹(tan(Angle_((Table 1)))*(W _(ball)/1.62)*(1.68/D_(ball))²)  (Eq. 10)

For example, Table 2 illustrates aerodynamic criteria for balls with adiameter of 1.60 inches and a weight of 1.7 ounces as calculated usingTable 1, ball diameter, ball weight, and Equations 9 and 10. TABLE 2AERODYNAMIC CHARACTERISTICS BALL DIAMETER = 1.60 INCHES, BALL WEIGHT =1.70 OUNCES Magnitude¹ Angle² (0) N_(Re) SR Low Median High Low MedianHigh 230000 0.085 0.24 0.265 0.27 31 33 35 207000 0.095 0.262 0.2870.297 38 40 42 184000 0.106 0.271 0.297 0.308 39 42 44 161000 0.122 0.830.311 0.322 42 44 46 138000 0.142 0.304 0.333 0.346 43 45 47 1150000.170 0.337 0.370 0.383 44 46 49  92000 0.213 0.382 0.420 0.435 45 47 50 69000 0.284 0.430 0.473 0.489 44 47 49¹As defined by Eq. 9²As defined by Eq. 10

Table 3 shows lift and drag coefficients (C_(L), C_(D)), as well asC_(mag) and Angle, for a golf ball having a nominal diameter of 1.68inches and a nominal weight of 1.61 ounces, with an icosahedron patternwith 392 dimples and two dimple diameters, of which the dimple patternwill be described in more detail below. The percent deviation in C_(mag)for PP and PH ball orientations are also shown over the range of N_(Re)and SR. The deviation in C_(mag) for the two orientations over theentire range is less than about 3 percent. TABLE 3 AERODYNAMICCHARACTERISTICS BALL DIAMETER = 1.68 INCHES, BALL WEIGHT = 1.61 OUNCES %PP Orientation PH Orientation Dev N_(Re) SR C_(L) C_(D) C_(mag) ¹ Angle²C_(L) C_(D) C_(mag) ¹ Angle² C_(mag) 230000 0.085 0.144 0.219 0.262 33.40.138 0.217 0.257 32.6 1.9 207000 0.095 0.159 0.216 0.268 36.3 0.1540.214 0.264 35.7 1.8 184000 0.106 0.169 0.220 0.277 37.5 0.166 0.2160.272 37.5 1.8 161000 0.122 0.185 0.221 0.288 39.8 0.181 0.221 0.28639.4 0.9 138000 0.142 0.202 0.232 0.308 41.1 0.199 0.233 0.306 40.5 0.5115000 0.170 0.229 0.252 0.341 42.2 0.228 0.252 0.340 42.2 0.2  920000.213 0.264 0.281 0.386 43.2 0.270 0.285 0.393 43.5 1.8  69000 0.2840.278 0.305 0.413 42.3 0.290 0.309 0.423 43.2 2.5 SUM 2.543 SUM 2.541¹As defined by Eq. 9²As defined by Eq. 10

Table 4 shows lift and drag coefficients (C_(L), C_(D)), as well asC_(mag) and Angle for a prior golf ball having a nominal diameter of1.68 inches and a nominal weight of 1.61 ounces. The percent deviationin C_(mag) for PP and PH ball orientations are also shown over the rangeof N_(Re) and SR. The deviation in C_(mag) for the two orientations isgreater than about 3 percent over the entire range, greater than about 6percent for N_(Re) of 161000, 138000, 115000, and 92000, and exceeds 10percent at a N_(Re) of 69000. TABLE 4 AERODYNAMIC CHARACTERISTICS FORPRIOR ART GOLF BALL BALL DIAMETER = 1.68 INCHES, BALL WEIGHT = 1.61OUNCES % PP Orientation PH Orientation Dev N_(Re) SR C_(L) C_(D) C_(mag)¹ Angle² C_(L) C_(D) C_(mag) ¹ Angle² C_(mag) 230000 0.085 0.151 0.2220.269 34.3 0.138 0.219 0.259 32.3 3.6 207000 0.095 0.160 0.223 0.27435.6 0.145 0.219 0.263 33.4 4.1 184000 0.106 0.172 0.227 0.285 37.20.154 0.221 0.269 34.8 5.6 161000 0.122 0.188 0.233 0.299 38.9 0.1660.225 0.279 36.5 6.9 138000 0.142 0.209 0.245 0.322 40.5 0.184 0.2310.295 38.5 8.7 115000 0.170 0.242 0.269 0.361 42.0 0.213 0.249 0.32840.5 9.7  92000 0.213 0.280 0.309 0.417 42.2 0.253 0.283 0.380 41.8 9.5 69000 0.284 0.270 0.308 0.409 41.2 0.308 0.337 0.457 42.5 10.9 SUM2.637 SUM 2.531¹As defined by Eq. 9²As defined by Eq. 10

Table 5 illustrates the flight performance of a golf ball of the presentinvention having a nominal diameter of 1.68 inches and weight of 1.61ounces, compared to a prior art golf ball having similar diameter andweight. Each prior art ball is compared to a golf ball of the presentinvention at the same speed, angle, and back spin. TABLE 5 BALL FLIGHTPERFORMANCE, INVENTION VS. PRIOR ART GOLF BALL BALL DIAMETER = 1.68INCHES, BALL WEIGHT = 1.61 OUNCES Launch Conditions Ball Rotation BallFlight Ball Speed Rate Distance Impact Orientation (mph) Angle (rpm)(yds) Time (s) Angle Prior Art PP 168.4 8.0 3500 267.2 7.06 41.4 PH168.4 8.0 3500 271.0 6.77 36.2 Invention PP 168.4 8.0 3500 276.7 7.1439.9 PH 168.4 8.0 3500 277.6 7.14 39.2 Prior Art PP 145.4 8.0 3000 220.85.59 31.3 PH 145.4 8.0 3000 216.9 5.18 25.4 Invention PP 145.4 8.0 3000226.5 5.61 29.3 PH 145.4 8.0 3000 226.5 5.60 28.7

Table 5 shows an improvement in flight distance for a golf ball of thepresent invention of between about 6 to about 10 yards over a similarsize and weight prior art golf ball. Table 5 also shows that the flightdistance of prior art golf balls is dependent on the orientation whenstruck, i.e., a deviation between a PP and PH orientation results inabout 4 yards distance between the two orientations. In contrast, golfballs of the present invention exhibit less than about 1 yard variationin flight distance due to orientation. Additionally, prior art golfballs exhibit large variations in the angle of ball impact with theground at the end of flight, i.e., about 5°, for the two orientations,while golf balls of the present invention have a variation in impactangles for the two orientations of less than about 1°. A large variationin impact angle typically leads to significantly different amounts ofroll when the ball strikes the ground.

The advantageously consistent flight performance of a golf ball of thepresent invention, i.e., the less variation in flight distance andimpact angle, results in more accurate play and potentially yields lowergolf scores. FIGS. 3 and 4 illustrate the magnitude of the aerodynamiccoefficients and the angle of aerodynamic force plotted versus N_(Re)for a golf ball of the present invention and a prior art golf ball, eachhaving a diameter of about 1.68 inches and a weight of about 1.61 ounceswith a fixed spin rate of 3000 rpm. As shown in FIG. 3, the magnitude ofthe aerodynamic coefficient is substantially lower and more consistentbetween orientations for a golf ball of the present invention ascompared to a prior art golf ball throughout the range of N_(Re) tested.FIG. 4 illustrates that the angle of the aerodynamic force is moreconsistent for a golf ball of the present invention as compared to aprior art golf ball.

A variety of golf ball sizes and weights, constructions, includingdimple patterns and profiles, and materials are contemplated to fit theaerodynamic characteristics as outlined in Table 1, and as modified fordifferent sizes and weights in accordance with Equations 9 and 10.Several non-limiting examples follow.

Dimple Patterns

One way of adjusting the magnitude of aerodynamic coefficients and angleof aerodynamic force for a ball to satisfy the aerodynamic criteria ofTable 1 is through different dimple patterns and profiles. As usedherein, the term “dimple”, may include any texturizing on the surface ofa golf ball, e.g., depressions and extrusions. Some non-limitingexamples of depressions and extrusions include, but are not limited to,spherical depressions, meshes; raised ridges, and brambles. Thedepressions and extrusions may take a variety of planform shapes, suchas circular, polygonal, oval, or irregular. Dimples that havemulti-level configurations, i.e., dimple within a dimple, are alsocontemplated by the invention to obtain desirable aerodynamiccharacteristics.

Dimple patterns that provide a high percentage of surface coverage arepreferred, and are well known in the art. For example, U.S. Pat. Nos.5,562,552, 5,575,477, 5,957,787, 5,249,804, and 4,925,193 disclosegeometric patterns for positioning dimples on a golf ball. In oneembodiment of the present invention, the dimple pattern is at leastpartially defined by phyllotaxis-based patterns, such as those describedU.S. Pat. No. 6,338,684, which is incorporated by reference in itsentirety. In one embodiment, a dimple pattern that provides greater thanabout 50 percent surface coverage is selected. In another embodiment,the dimple pattern provides greater than about 70 percent surfacecoverage, and more preferably, the dimple surface coverage is greaterthan 80 percent.

Several additional non-limiting examples follow of different dimplepattern geometries that may be used to obtain the aerodynamic criteriaof Table 1.

FIGS. 5 and 6 show the TITLEIST PROFESSIONAL golf ball 10 with aplurality of dimples 11 on the outer surface that are formed into adimple pattern having two sizes of dimples. The first set of dimples Ahave diameters of about 0.14 inches and form the outer triangle 12 ofthe icosahedron dimple pattern. The second set of dimples B havediameters of about 0.16 inches and form the inner triangle 13 and thecenter dimple 14. The dimples 11 cover less than 80 percent of the outersurface of the golf ball and there are a significant number of largespaces 15 between adjacent dimples, i.e., spaces that could hold adimple of 0.03 inches diameter or greater.

FIGS. 7 and 8 show a golf ball 20 according to the first dimple patternembodiment of the present invention with a plurality of dimples 21 in anicosahedron pattern. In an icosahedron pattern, there are twentytriangular regions that are generally formed from the dimples. Theicosahedron pattern has five triangles formed at both the top and bottomof the ball, each of which shares the pole dimple as a point. There arealso ten triangles that extend around the middle of the ball.

In this first dimple pattern embodiment, there are five different sizeddimples A-E, wherein dimples E (D_(E)) are greater than dimples D(D_(D)), which are greater than dimples C (D_(C)), which are greaterthan dimples B(D_(B)), which are greater than dimples A (D_(A));D_(E)>D_(D)>D_(C)>D_(B)>D_(A). Dimple minimum sizes according to thisembodiment are set forth in TABLE 6 DIMPLE SIZES FOR FIRST DIMPLEPATTERN EMBODIMENT Percent of Ball Dimple Diameter A 6.55 B 8.33 C 9.52D 10.12 E 10.71

The dimples of this embodiment are formed in large triangles 22 andsmall triangles 23. The dimples along the sides of the large triangle 22increase in diameter toward the midpoint 24 of the sides. The largestdimple along the sides, D_(E), is located at the midpoint 24 of eachside of the large triangle 22, and the smallest dimples, D_(A), arelocated at the triangle points 25. In this embodiment, each dimple alongthe sides is larger than the adjacent dimple toward the triangle point.

FIGS. 9-12 illustrate a second dimple pattern embodiment contemplatedfor the golf ball of the present invention. In this embodiment, thereare again five different sized dimples A-E, wherein dimples E (D_(E))are greater than dimples D (D_(D)), which are greater than dimples C(D_(C)), which are greater than dimples B(D_(B)), which are greater thandimples A (D_(A)); D_(E)>D_(D)>D_(C)>D_(B)>D_(A). Dimple minimum sizesaccording to this embodiment are set forth in Table 7 below: TABLE 7DIMPLE SIZES FOR SECOND DIMPLE PATTERN EMBODIMENT Percent of Ball DimpleDiameter A 6.55 B 8.93 C 9.23 D 9.52 E 10.12

In the second dimple pattern embodiment, the dimples are again formed inlarge triangles 22 and small triangles 23 as shown in FIG. 11. Thedimples along the sides of the large triangle 22 increase in diametertoward the midpoint 24 of the sides. The largest dimple along the sides,D_(D), is located at the midpoint 24 of each side of the large triangle22, and the smallest dimples, D_(A), are located at the triangle points25. In this embodiment, each dimple along the sides is larger than theadjacent dimple toward the triangle point, i.e., D_(B)>D_(A) andD_(D)>D_(B)

A third dimple pattern embodiment is illustrated in FIGS. 13-14, whereinthe golf ball has an octahedral dimple pattern. In an octahedral dimplepattern, there are eight spherical triangular regions 30 that form theball. In this third dimple pattern embodiment, there are six differentsized dimples A-F, wherein dimples F (D_(F)) are greater than dimples E(D_(E)), which are greater than dimples D (D_(D)), which are greaterthan dimples C (D_(C)), which are greater than dimples B(D_(B)), whichare greater than dimples A (D_(A)); D_(F)>D_(E)>D_(D)>D_(C)>D_(B)>D_(A). Dimple minimum sizes according to thisembodiment are set forth in Table 8 below: TABLE 8 DIMPLE SIZES FORTHIRD DIMPLE PATTERN EMBODIMENT Percentage of Ball Dimple Diameter A5.36 B 6.55 C 8.33 D 9.83 E 9.52 F 10.12

In this third dimple pattern embodiment, the dimples are formed in largetriangles 31, small triangles 32 and smallest triangles 33. Each dimplealong the sides of the large triangle 31 is equal to or larger than theadjacent dimple from the point 34 to the midpoint 35 of the triangle 31.The dimples at the midpoint 35 of the side, D_(E), are the largestdimples along the side and the dimples at the points 34 of the triangle,D_(A), are the smallest. In addition, each dimple along the sides of thesmall triangle 32 is also equal to or larger than the adjacent dimplefrom the point 36 to the midpoint 37 of the triangle 32. The dimple atthe midpoint 37 of the side, D_(F), is the largest dimple along the sideand the dimples at the points 36 of the triangle, D_(C), are thesmallest.

Dimple Packing

In one embodiment, the golf balls of the invention include anicosahedron dimple pattern, wherein each of the sides of the largetriangles are formed from an odd number of dimples and each of the sideof the small triangles are formed with an even number of dimples.

For example, in the icosahedron pattern shown in FIGS. 7-8 and 9-12,there are seven dimples along each of the sides of the large triangle 22and four dimples along each of the sides of the small triangle 23. Thus,the large triangle 22 has nine more dimples than the small triangle 23,which creates hexagonal packing 26, i.e., each dimple is surrounded bysix other dimples for most of the dimples on the ball. For example, thecenter dimple, D_(E), is surrounded by six dimples slightly smaller,D_(D). In one embodiment, at least 75 percent of the dimples have 6adjacent dimples. In another embodiment, only the dimples forming thepoints of the large triangle 25, D_(A), do not have hexagonal packing.Since D_(A) are smaller than the adjacent dimples, the gaps betweenadjacent dimples is surprisingly small when compared to the prior artgolf ball shown in FIG. 7.

The golf ball 20 has a greater dispersion of the largest dimples. Forexample, in FIG. 7, there are four of the largest diameter dimples,D_(E), located in the center of the triangles and at the mid-points ofthe triangle sides. Thus, there are no two adjacent dimples of thelargest diameter. This improves dimple packing and aerodynamicuniformity. Similarly, in FIG. 9, there is only one largest diameterdimple, D_(E), which is located in the center of the triangles. Even thenext to the largest dimples, D_(D) are dispersed at the mid-points ofthe large triangles such that there are no two adjacent dimples of thetwo largest diameters, except where extra dimples have been added alongthe equator.

In the third dimple pattern embodiment, each of the sides of the largetriangle 31 has an even number of dimples, each of the sides of thesmall triangle 32 has an odd number of dimples and each of the sides ofthe smallest triangle 33 has an even number of dimples. There are tendimples along the sides of the large triangles 31, seven dimples alongthe sides of the small triangles 32, and four dimples along the sides ofthe smallest triangles 33. Thus, the large triangle 31 has nine moredimples than the small triangle 32 and the small triangle 32 has ninemore dimples than the smallest triangle 33. This creates the hexagonalpacking for all of the dimples inside of the large triangles 31.

As used herein, adjacent dimples can be considered as any two dimpleswhere the two tangent lines from the first dimple that intersect thecenter of the second dimple do not intersect any other dimple. In oneembodiment, less than 30 percent of the gaps between adjacent dimples isgreater than 0.01 inches. In another embodiment, less than 15 percent ofthe gaps between adjacent dimples is greater than 0.01 inches.

One embodiment of the present invention contemplates dimple coverage ofgreater than about 80 percent. For example, the percentages of surfacearea covered by dimples in the embodiments shown in FIGS. 7-8 and 9-12are about 85.7 percent and 82 percent, respectively whereas the ballshown in FIG. 5 has less than 80 percent of its surface covered bydimples. The percentage of surface area covered by dimples in the thirdembodiment shown in FIGS. 13-14 is also about 82 percent, whereas priorart octahedral balls have less than 77 percent of their surface coveredby dimples, and most have less than 60 percent. Thus, there is asignificant increase in surface area contemplated for the golf balls ofthe present invention as compared to prior art golf balls.

Parting Line

A parting line, or annular region, about the equator of a golf ball hasbeen found to separate the flow profile of the air into two distincthalves while the golf ball is in flight and reduce the aerodynamic forceassociated with pressure recovery, thus improving flight distance androll. The parting line must coincide with the axis of ball rotation. Itis possible to manufacture a golf ball without parting line, however,most balls have one for ease of manufacturing, e.g., buffing of the golfballs after molding, and many players prefer to have a parting line touse as an alignment aid for putting.

In one embodiment of the present invention, the golf balls include adimple pattern containing at least one parting line, or annular region.In another embodiment, there is no parting line that does not intersectany dimples, as illustrated in the golf ball shown in FIG. 7. While thisincreases the percentage of the outer surface that is covered bydimples, the lack of the parting line may make manufacturing moredifficult.

In yet another embodiment, the parting line(s) may include regions of nodimples or regions of shallow dimples. For example, most icosahedronpatterns generally have modified triangles around the mid-section tocreate a parting line that does not intersect any dimples. Referringspecifically to FIG. 12, the golf ball in this embodiment has a modifiedicosahedron pattern to create the parting line 27, which is accomplishedby inserting an extra row of dimples. In the triangular sectionidentified with lettered dimples, there is an extra row 28 of D-C-C-Ddimples added below the parting line 27. Thus, the modified icosahedronpattern in this embodiment has thirty more dimples than the unmodifiedicosahedron pattern in the embodiment shown in FIGS. 7-8.

In another embodiment, there are more than two parting lines that do notintersect any dimples. For example, the octahedral golf ball shown inFIGS. 13-14 contains three parting lines 38 that do not intersect anydimples. This decreases the percentage of the outer surface as comparedto the first embodiment, but increases the symmetry of the dimplepattern.

In another embodiment, the golf balls according to the present inventionmay have the dimples arranged so that there are less than four partinglines that do not intersect any dimples.

Dimple Count

In one embodiment, the golf balls according to the present inventionhave about 300 to about 500 total dimples. In another embodiment, thedimple patterns are icosahedron patterns with about 350 to about 450total dimples. For example, the golf ball of FIGS. 7-8 have 362 dimples.In the golf ball shown in FIGS. 9-12, there are 392 dimples and in thegolf ball shown in FIGS. 13-14, there are 440 dimples.

Dimple Diameter

In one embodiment, at least about 80 percent of the dimples have adiameter of about 6.5 percent of the ball diameter or greater so thatthe majority of the dimples are sufficiently large to assist in creatingthe turbulent boundary layer. In another embodiment, at least about 90percent of the dimples have a diameter of about 6.5 percent of the balldiameter or greater. In yet another embodiment, at least about 95percent of the dimples have a diameter of about 6.5 percent of the balldiameter or greater. For example, all of the dimples have a diameter ofabout 6.5 percent of the ball diameter or greater in the ballillustrated by FIGS. 9-12.

Dimple Profile

Golf balls may also be designed to fit the aerodynamic criteria of Table1 by creating dimple patterns wherein all dimples have fixed radii anddepth, but vary as to shape. For example, dimple shape variations may bedefined as edge radius and edge angle or by catenary shape factor andedge radius.

In one embodiment, a golf ball of the present invention meets thecriteria of Table 1 by including dimples defined by the revolution of acatenary curve about an axis. A catenary curve represents the curveformed by a perfectly flexible, uniformly dense, and inextensible cablesuspended from its endpoints. In general, the mathematical formularepresenting such a curve is expressed as Equation 11:y=a cos h(bx)  (Eq. 11)where

a=constant

b=constant

y=vertical axis (on a two dimensional graph)

x=horizontal axis (on a two dimensional graph)

The dimple shape on the golf ball is generated by revolving the catenarycurve about its y axis.

This embodiment uses variations of Equation 11 to define thecross-section of golf ball dimples. For example, the catenary curve isdefined by hyperbolic sine or cosine functions. A hyperbolic sinefunction is expressed as Equation 12 below:

sin h(x)=(e ^(x) −e ^(−x))/2  (Eq. 12)

while a hyperbolic cosine function is expressed by Equation 13:cos h(x)=(e ^(x) +e ^(−x))/2  (Eq. 13)

In one embodiment, the mathematical equation for describing thecross-sectional profile of a dimple is expressed by Equation 14:Y=(d(cos h(ax)−1))/(cos h(ar)−1)  (Eq. 14)where

Y=vertical distance from the dimple apex

x=radial distance from the dimple apex to the dimple surface

a=shape constant (shape factor)

d=depth of dimple

r=radius of dimple

The “shape constant” or “shape factor”, a, is an independent variable inthe mathematical expression for a catenary curve. The shape factor maybe used to independently alter the volume ratio of the dimple whileholding the dimple depth and radius fixed. The volume ratio is thefractional ratio of the dimple volume divided by the volume of acylinder defined by a similar radius and depth as the dimple.

Use of the shape factor provides an expedient method of generatingalternative dimple profiles, for dimples with fixed radii and depth. Forexample, to design a golf ball with lift and drag characteristics to fitthe aerodynamic criteria of Table 1, alternative shape factors may beemployed to obtain alternative lift and drag performance without havingto change dimple pattern, depth or size. No modification to the dimplelayout on the surface of the ball is required.

The depth (d) and radius (r) (r=½ D) of the dimple may be measured asdescribed in U.S. Pat. No. 4,729,861 (shown in FIG. 15), the disclosureof which is incorporated by reference in its entirety. The dimplediameter is measured from the edges of the dimples, points E and F,along straight line 162. Point J is the deepest part of the dimple 12.The depth is measured from point K on the continuation of the periphery41 to point J and is indicated by line 164. Line 164 is perpendicular toline 162.

For Equation 14, shape constant values that are larger than 1 result indimple volume ratios greater than 0.5. In one embodiment, shape factorsare between about 20 to about 100. FIGS. 16-20 illustrate dimpleprofiles for shape factors of 20, 40, 60, 80, and 100, respectively.Table 9 illustrates how the volume ratio changes for a dimple with aradius of 0.05 inches and a depth of 0.025 inches. Increases in shapefactor result in higher volume ratios for a given dimple radius anddepth. It has been discovered that the use of dimples with multiplecatenary shape factors may be used to obtain the aerodynamic criteria ofTable 1 and the symmetry requirements of less than 6 percent variationC_(mag). TABLE 9 VOLUME RATIO AS A FUNCTION OF RADIUS AND DEPTH SHAPEFACTOR VOLUME RATIO 20 0.51 40 0.55 60 0.60 80 0.64 100 0.69

A dimple whose profile is defined by the cosh catenary curve with ashape constant of less than about 40 will have a smaller dimple volumethan a dimple with a spherical profile. This will result in a largeraerodynamic force angle and higher trajectory. On the other hand, adimple whose profile is defined by the cosh catenary curve with a shapeconstant of greater than about 40 will have a larger dimple volume thana dimple with a spherical profile. This will result in a smaller angleof the aerodynamic force and a lower trajectory. Therefore, a golf ballhaving dimples defined by a catenary curve with a shape constant isadvantageous because the shape constant may be selected to obtain theaerodynamic criteria delineated in Table 1.

While this embodiment is directed toward using a catenary curve for atleast one dimple on a golf ball, it is not necessary that catenarycurves be used on every dimple on a golf ball. In some cases, the use ofa catenary curve may only be used for a small number of dimples. It ispreferred, however, that a sufficient number of dimples on the ball havecatenary curves so that variation of shape factors will allow a designerto alter the aerodynamic characteristics of the ball to satisfy theaerodynamic criteria of Table 1. In one embodiment, the golf ball has atleast about 10 percent, and more preferably at least about 60 percent,of its dimples defined by a catenary curves.

Moreover, it is not necessary that every dimple have the same shapefactor. Instead, differing combinations of shape factors for differentdimples on the ball may be used to achieve desired ball flightperformance. For example, some of the dimples defined by catenary curveson a golf ball may have one shape factor while others have a differentshape factor. In addition, the use of differing shape factors may beused for different diameter dimples, as described above in FIGS. 6-14.

Therefore, once a dimple pattern is selected for the golf ball,alternative shape factors for the catenary profile can be tested inlight gate test range, as described in U.S. Pat. No. 6,186,002, toempirically determine the catenary shape factor that provides thedesired aerodynamic characteristics of Table 1.

Aerodynamic Symmetry

To create a ball that adheres to the Rules of Golf, as approved by theUnited States Golf Association, the ball must not be designed,manufactured or intentionally modified to have properties that differfrom those of a spherically symmetrical ball. Aerodynamic symmetryallows the ball to fly with little variation no matter how the golf ballis placed on the tee or ground.

Dimple patterns are preferably designed to cover the maximum surfacearea of the golf ball without detrimentally affecting the aerodynamicsymmetry of the golf ball. A representative coordinate system used tomodel some of the dimple patterns discussed above is shown in FIG. 21.The XY plane is the equator of the ball while the Z direction goesthrough the pole of the ball. Preferably, the dimple pattern isgenerated from the equator of the golf ball, the XY plane, to the poleof the golf ball, the Z direction.

As discussed above, golf balls containing dimple patterns having aparting line about the equator may result in orientation specific flightcharacteristics. As mentioned above, the parting lines are desired bymanufacturers for ease of production, as well as by many golfers forlining up a shot for putting or off the tee. It has now been discoveredthat selective design of golf balls with dimple patterns including aparting line meeting the aerodynamic criteria set forth in Table 1result in flight distances far improved over prior art. Geometrically,these parting lines must be orthogonal with the axis of rotation.However, in one embodiment of the present invention, there may be aplurality of parting lines with multiple orientations.

In one embodiment, the aerodynamic coefficient magnitude for a golf ballvaries less than about 6 percent whether a golf ball has a PH or PPorientation. In another embodiment, the variation of the aerodynamiccoefficient magnitude between the two orientations is less than about 3percent.

Ball Construction

The present invention may be used with any type of ball construction.For example, the ball may have a 1-piece design, a 2-piece design, athree-piece design, a double core, a double cover, or multi-core andmulti-cover construction depending on the type of performance desired ofthe ball. Non-limiting examples of these and other types of ballconstructions that may be used with the present invention include thosedescribed in U.S. Pat. Nos. 5,688,191, 5,713,801, 5,803,831, 5,885,172,5,919,100, 5,965,669, 5,981,654, 5,981,658, and 6,149,535, as well as inPublication No. US2001/0009310 A1. The entire disclosures of theseapplications are incorporated by reference herein.

Different materials also may be used in the construction of the golfballs made with the present invention. For example, the cover of theball may be made of a thermoset or thermoplastic, a castable ornon-castable polyurethane and polyurea, an ionomer resin, balata, or anyother suitable cover material known to those skilled in the art.Different materials also may be used for forming core and intermediatelayers of the ball. For example, golf balls having solid, wound, liquidfilled, dual cores, and multi-layer intermediate components arecontemplated by the invention. For example, the most common corematerial is polybutadiene, although one of ordinary skill in the art isaware of the various materials that may be used with the presentinvention. After selecting the desired ball construction, theaerodynamic performance of the golf ball designed to satisfy theaerodynamic criteria outlined in Table 1 according to the design,placement, and number of dimples on the ball.

As explained above, the use of various dimple patterns and profilesprovides a relatively effective way to modify the aerodynamiccharacteristics. The use of the catenary curve profile allows a golfball design to meet the aerodynamic criteria of Table 1 withoutsignificantly altering the dimple pattern. Different materials and ballconstructions can also be selected to achieve a desired performance.

While it is apparent that the illustrative embodiments of the inventionherein disclosed fulfill the objectives stated above, it will beappreciated that numerous modifications and other embodiments such astetrahedrons having four triangles may be devised by those skilled inthe art. Therefore, it will be understood that the appended claims areintended to cover all such modifications and embodiments which comewithin the spirit and scope of the present invention.

1. A golf ball with a plurality of dimples having an aerodynamiccoefficient magnitude defined by C_(mag)=√(C_(L) ²+C_(D) ²) and anaerodynamic force angle defined by Angle=tan⁻¹ (C_(L)/C_(D)), whereinC_(L) is a lift coefficient and C_(D) is a drag coefficient, and whereinC_(L) is at least one of about 0.151 at a pole over pole orientation orabout 0.138 at a poles horizontal orientation at a Reynolds Number ofabout 230000 and a spin ratio of about 0.085.
 2. The golf ball of claim1, wherein C_(D) is at least one of about 0.222 at a pole over poleorientation or about 0.219 at a poles horizontal orientation at aReynolds Number of about 230000 and a spin ratio of about 0.085.
 3. Thegolf ball of claim 1, wherein C_(L) is at least one of about 0.160 at apole over pole orientation or about 0.145 at a poles horizontalorientation at a Reynolds Number of about 207000 and a spin ratio ofabout 0.095.
 4. The golf ball of claim 1, wherein the golf ball has atleast one of a first aerodynamic coefficient magnitude of about 0.269 ata pole over pole orientation or a first aerodynamic coefficientmagnitude of about 0.259 at a poles horizontal orientation at a ReynoldsNumber of about 230000 and a spin ratio of about 0.085.
 5. The golf ballof claim 1, wherein the golf ball has at least one of a firstaerodynamic coefficient magnitude of about 0.274 at a pole over poleorientation or a first aerodynamic coefficient magnitude of about 0.263at a poles horizontal orientation at a Reynolds Number of about 207000and a spin ratio of about 0.095.
 6. The golf ball of claim 1, whereinthe golf ball has at least one of a first aerodynamic force angle ofabout 34.3 at a pole over pole orientation or a first aerodynamic forceangle of about 32.3 at a poles horizontal orientation at a ReynoldsNumber of about 230000 and a spin ratio of about 0.085.
 7. The golf ballof claim 6, wherein the golf ball has at least one of a secondaerodynamic force angle of about 35.6 at a pole over pole orientation ora second aerodynamic force angle of about 33.4 at a poles horizontalorientation at a Reynolds Number of about 207000 and a spin ratio ofabout 0.095.
 8. A golf ball with a plurality of dimples having anaerodynamic coefficient magnitude defined by C_(mag)=√(C_(L) ²+C_(D) ²)and an aerodynamic force angle defined by Angle=tan⁻¹(C_(L)/C_(D)),wherein C_(L) is a lift coefficient and C_(D) is a drag coefficient,wherein C_(L) is at least one of about 0.27 at a pole over poleorientation or about 0.308 at a poles horizontal orientation at aReynolds Number of about 69000 and a spin ratio of about 0.284.
 9. Thegolf ball of claim 8, wherein C_(L) is at least one of about 0.28 at apole over pole orientation or about 0.253 at a poles horizontalorientation at a Reynolds Number of about 92000 and a spin ratio ofabout 0.213.
 10. The golf ball of claim 8, wherein C_(L) is at least oneof about 0.242 at a pole over pole orientation or about 0.213 at a poleshorizontal orientation at a Reynolds Number of about 115000 and a spinratio of about 0.17.
 11. The golf ball of claim 8, wherein C_(D) is atleast one of about 0.308 at a pole over pole orientation or about 0.337at a poles horizontal orientation at a Reynolds Number of about 69000and a spin ratio of about 0.284.
 12. The golf ball of claim 8, whereinthe golf ball has a first aerodynamic coefficient magnitude of about0.40 to about 0.45 at a Reynolds Number of about 69000 and a spin ratioof about 0.284.
 13. The golf ball of claim 12, wherein the golf ball hasa second aerodynamic coefficient magnitude of about 0.36 to about 0.40at a Reynolds Number of about 92000 and a spin ratio of about 0.213. 14.A golf ball with a plurality of dimples having an aerodynamiccoefficient magnitude defined by C_(mag)=√(C_(L) ²+C_(D) ²) and anaerodynamic force angle defined by Angle=tan⁻¹(C_(L)/C_(D)), whereinC_(L) is a lift coefficient and C_(D) is a drag coefficient, and whereinC_(L) is at least one of about 0.151 at a pole over pole orientation orabout 0.138 at a poles horizontal orientation at a Reynolds Number ofabout 230000 and a spin ratio of about 0.085, and wherein the golf ballhas a first aerodynamic coefficient magnitude of about 0.24 to about0.27 at a Reynolds Number of about 230000 and a spin ratio of about0.085.
 15. The golf ball of claim 14, wherein the golf ball has a secondaerodynamic coefficient magnitude of about 0.25 to about 0.28 at aReynolds Number of about 207000 and a spin ratio of about 0.095.
 16. Thegolf ball of claim 14, wherein C_(L) is at least one of about 0.160 at apole over pole orientation or about 0.145 at a poles horizontalorientation at a Reynolds Number of about 207000 and a spin ratio ofabout 0.095.
 17. The golf ball of claim 14, wherein the golf ball has atleast one of a first aerodynamic force angle of about 31 to about 35 ata Reynolds Number of about 230000 and a spin ratio of about 0.085. 18.The golf ball of claim 17, wherein the golf ball has at least one of afirst aerodynamic force angle of about 34 to about 38 at a ReynoldsNumber of about 207000 and a spin ratio of about 0.095.